索引【备档】

1.索引CREATE INDEX mytable_categoryid_userid_adddate ON mytable (category_id,user_id,adddate);

2.存储过程：

create Procedure GetUserAccountRe2
@UserName nchar(20),
@UserID int output
as
if(@UserName>5)
select @UserID=COUNT(*) from UserAccount where UserID>25
else
set @UserID=1000
select * from UserAccount
return @@rowcount
go

create procedure getsum

@n int =0<--此处为参数-->

as

declare @sum int<--定义变量-->

declare @i int

set @sum=0

set @i=0

while @i<=@n begin

set @sum=@sum+@i

set @i=@i+1

end

print 'the sum is '+ltrim(rtrim(str(@sum)))

3.游标，正在学：

4.触发器

触发器感觉可以做成双层校验，一层是数据库直接校验，另外一层是在程序封装一层做校验，防止有人通过数据库直接改，。

create trigger truStudent
on UserYSXQ.dbo.Student
for update
as
if UPDATE(studentid)
begin
update BorrowRecord
set studentid=i.studentid from borrowRecord br,deleted d,inserted i where br.studentid=d.studentid
end

5.

插入数据可以这样插入

INSERT INTO 卷烟库存表(卷烟品牌,库存数量,库存单价,库存金额)
SELECT '红塔山新势力',100,12,1200 UNION ALL
SELECT '红塔山人为峰',100,22,NULL UNION ALL
SELECT '云南映像',100,60,500 UNION ALL
SELECT '玉溪',0,30,0
GO